Green Chemistry in the 21st Century

The growing influence of chemistry’s own environmental movement

The university admissions interview I remember most clearly was at the University of Nottingham. Like all the other interviews I had during that period, I went in expecting to be asked what chemistry topics I enjoyed learning about, or perhaps something more technical on thermodynamics or balancing reaction equations. Instead, the professor invited me to imagine sitting in a bar in my first week at university, talking with my fellow freshers about the subjects we were studying. One of them, he continued, would challenge me when I said I studied chemistry, claiming that because of pollution and climate change, it was destroying the world. “What,” my interviewer asked, “would be my response?”

Over a decade later, I remember the question more than my answer, but the message is one I have grown to appreciate. All chemists are aware of the negative attention our science receives, sometimes with good reason; if anything, the chemical industry often appears as the complete antithesis of environmentalism. Yet our modern way of life is totally dependent on an industry that manufactures billions of tonnes of chemicals (and produces millions of tonnes of pollution) each year. The future will see us become even more reliant on chemistry as we aim to provide enough energy, food and medication for our growing and aging population. If any industry needs an environmental movement, it’s the chemical industry. Fortunately, it has one and its called Green Chemistry.

Green Chemistry, like many modern environmental movements, can trace its origins back to Rachel Carson’s Silent Spring, which first connected the use of chemical pesticides with the loss of wildlife. Green Chemistry only began to gain momentum during the 1990s thanks to a young EPA staff chemist Paul Anastas, who coined the term and created both its guiding philosophy and core principles.

Anastas’ vision was a paradigm shift in the design of chemical processes. Up to then, attempts to prevent pollution centred entirely on what is termed “end-of-pipe” clean up: a kind of industrial Elastoplast. If the Elastoplast is only partially effective, the environment is slowly exposed to tonnes of hazardous chemicals; if it fails completely, the outcome can be disastrous. Anastas proposed that chemists should seek to avoid any toxic or dangerous chemicals from the outset. Then, if something does go wrong, any pollution will be minimal or, hopefully, non-existent. This concept was codified in his 12 principles of Green Chemistry, and a range of metrics quantifying the “green-ness” of a chemical process followed.

If the philosophy of Green Chemistry is to translate into tangible environmental benefits then it needs industrial acceptance. One new metric, the “E-factor” quickly established itself as a measure of chemical wastefulness and the pharmaceutical industry was identified as a particularly bad offender. When we think of pharmaceuticals, we probably imagine rows of perfectly formed tablets zipping along production lines, or scientists working in immaculately clean laboratories. We are perhaps less aware of the tonnes of acids and bases, chlorinated solvents and heavy metals that are used to produce our medicines. For every kilogram of drug manufactured, up to a tonne of these chemicals end up as waste; waste that has to be destroyed, stored or disposed of by other means. The fear of litigation is also ever-present, making the industry increasingly wary of using any chemicals that might present a risk to human health. Many pharmaceutical chemists now realise that Green Chemistry not only makes environmental sense, but business sense and 20 years on the industry is seen as a success story.

Although it has readily adopted Green Chemistry, the pharmaceuticals have a relatively small footprint compared to other sectors of the chemical industry. In contrast, the processes needed to convert oil into petrochemicals are relatively efficient but occur on a vast scale, consuming similarly vast amounts of energy and producing similarly vast amounts of waste. Replacing a megatonne industrial process with a greener alternative requires both long-term technical development and convincing conservative boardrooms to part with significant amounts of cash. This might explain why market research estimates the current value of Green Chemistry is only $2.8bn in a trillion dollar chemical industry. There are reasons to be optimistic: implementing new technologies takes time and many of those currently being developed will soon come online. Forecasts suggest that Green Chemistry’s worth will reach $100bn by 2020.

Despite this apparent success, many environmentalists remain sceptical about the genuine green commitment within the industry. New regulatory frameworks, including the EU’s REACH and California’s Green Chemistry Initiative, have faced pushback, while recent WHO reports on endocrine disruptors will not ease public fears about persistent harmful chemicals in the environment.

Hydraulic fracturing (fracking) for shale gas also raises questions for Green Chemists. We are all aware of the bad press around the risks of fracking chemicals entering water streams, and, even if these risks are overplayed, finding less harmful alternatives would be a step in the right direction. It is, however, the challenge fracking presents to one of its core principles that should make Green Chemists sit up and take note.

From plastics to pharmaceuticals most of our chemicals come from crude oil and other non-renewable resources. The concerns over dwindling oil supplies and ever-increasing prices led to research into “biorenewable” feedstocks, essentially converting plant matter into useful chemicals. If fracking provides the new, cheap supplies of energy and petrochemicals many in the industry hopes it will, the development of biorenewables may be hampered. How Green Chemists respond to fracking will most likely determine how the field is viewed by the industry it aims to help.

Where does the future of Green Chemistry lie? Its principles need to go beyond the confines of the traditional chemical and pharmaceutical industries: manufacturing, construction and energy all use their fair share of chemicals too. Even some clean technologies could use a Green Chemistry makeover, for example solar panels are made from silicon in processes that eat energy. Finally, it is us-the public, the consumer, the end-user- who would benefit most from a better understanding of Green Chemistry and its principles. It is, after all, how we use and dispose of chemicals that often causes the most environmental damage.